Results from the Golestan Cohort Study (GCS), reported in Lancet Global Health, confirm that opiates can have cancerogenic long-term effects and that their over-use should be discouraged.
The population-based prospective study involved 50,034 participants of whom 8,486 used opium. At a median follow-up of 10 years, 1,833 participants were diagnosed with cancer.
According to the authors, the median duration of opium use was 10.4 years, most commonly raw opium, and the most common route of administration was smoking. Users tended to be older males of Turkman ethnicity, living in rural areas, and having lower wealth. They also had more unhealthy diets, burned biomass as household fuel, smoked cigarettes, chewed nass, and consumed alcohol more than people who did not use opium.
Opium use was associated with an increased risk of developing oesophageal (HR 1.38; 95% CI 1.06-1.80), gastric (1.36; 1.03-1.79), lung (2.21; 1.44-3.39), bladder (2.86; 1.47-5.55), and laryngeal (2.53; 1.21-5.30) cancers in a dose-response manner. High-dose opium use was associated with pancreatic cancer (2.66; 1.23-5.74). Additionally, the associations were stronger for opium smoking with oesophageal cancer and gastric cancer, while the associations for opium ingestion were stronger with brain cancer and liver cancer.